Improved lead acid battery separators and batteries containing the same

ABSTRACT

Disclosed in at least one embodiment herein is a battery separator comprising a substrate that may be polymeric and porous. The substrate may have ribs, protrusions, or ribs and protrusions on one or both faces or surfaces thereof. On at least one surface or face of the substrate, a material layer may be formed. The material layer may contain a material with an oil absorption value equal to or greater than 15 g oil/100 g of material. The battery separator disclosed herein is useful in a lead acid battery, particularly in a flooded lead acid battery or a valve-regulated lead acid (VRLA) battery. The battery separator described herein has many benefits including helping mitigate or prevent issues such as acid stratification and others that may deteriorate battery performance or battery life.

FIELD

The present disclosure relates to novel or improved separators for avariety of lead acid batteries and/or systems. In addition, exemplaryembodiments disclosed herein are directed to novel or improved batteryseparators, battery cells incorporating the same, batteriesincorporating the same, systems incorporating the same, and/or methodsof manufacturing and/or of using the same, and/or the like, and/orcombinations thereof.

BACKGROUND

The lead acid battery is a highly economical solution to energy storageand has been the preferred energy source of starting vehicles forapproximately 100 years. During most of these 100 years, the primaryrole of the lead acid battery has been to simply start the engine a fewtimes a day and then provide power for emergency lighting when and ifthe vehicle became disabled because of an engine malfunction. To start avehicle, the lead acid battery typically discharges less than 5% of itsfull capacity and soon recharges to 100% charge by the operationalengine. Thus, the traditional lead acid battery used in automotiveapplications has typically operated at 100% charge.

In order to improve fuel economy and reduce tailpipe emissions,manufacturers have designed vehicles, generally called Idle Stop-Start(“ISS”) vehicles, such that their engines turn off more frequently. ISSvehicle engines turn off when the vehicle has stopped, and automaticallyrestart when it is time for the vehicle to be mobile again. Typically,the engine restarts upon the release of the brake pedal. In addition torestarting the engine, ISS vehicle batteries are required to provideenergy for vehicle accessories when the engine is off. Such exemplaryaccessories may be the HVAC system, heated seats, radios, lights, andthe like. When these vehicles operate in stop-and-go traffic, such asthat in a city setting or other congested areas, the lead acid batterytypically operates in a partial state of charge (“PSoC”) and may never(or rarely) experience a fully charged condition. A PSoC exists when abattery operates at a charge of less than 100%, and typically continuesin this manner through multiple discharge and charge cycles withoutreaching a 100% charge. This operation in a PSoC has highlighted allmanner of weaknesses in the current state of the art in lead acidbattery technology. Thus, there currently remain unmet needs in leadacid battery technology.

Referring to FIG. 1 , a typical lead acid battery 50 has a positiveterminal 51 and a negative terminal 53. The terminals 51, 53 aretypically disposed on the top or side of the battery 50. Within thebattery, an electrode/separator array 50 a encompasses alternatingpositive electrodes 52 and negative electrodes 54, and a porous ormicroporous separator 100 disposed and interleaved between each positiveelectrode 52 and negative electrode 54. The positive terminal 51 is inelectrical communication with the positive electrodes 52. Likewise, thenegative terminal 53 is in electrical communication with the negativeelectrodes 54. The separators 100 are shown with leaf or cut-pieceseparators 100, however they may alternatively be formed as positiveenvelopes (i.e., enveloping the positive electrodes), negative envelopes(i.e., enveloping the negative electrodes), hybrid envelopes, pockets,sleeves, wraps, and/or the like, and/or a combination thereof.Typically, the separator may comprise a microporous silica filledpolyethylene (PE) membrane separator having backweb 102 or 202 or abackweb (102 or 202) and ribs or protrusions 104. 102 n or 202 n denotesa negative face or surface of the backweb and 102 p or 202 p denotes apositive face or surface of the backweb.

Typical positive electrodes 52 have a current carrying grid, madepredominately of lead dioxide (PbO₂), and typically doped with apositive active material (“PAM”). Typical negative electrodes 54 have acurrent carrying grid, made predominately of lead (Pb), and typicallydoped with a negative active material (“NAM”). Both of the PAM and NAMcontribute to increasing the functionality of the electrodes. Thepositive and negative grids may encompass alloys having at least one ofantimony (Sb), calcium (Ca), tin (Sn), selenium (Se), and/or the like,or a combination thereof.

An aqueous electrolyte 56 solution substantially submerges theelectrodes 52, 54 and separators 100. In lead acid batteries, theelectrolyte 56 solution acts as both an electrolyte and as a reactant,and is typically a solution of water and sulfuric acid (H₂SO₄). Theelectrolyte solution typically has an optimal specific gravity ofapproximately 1.280 (1280 Kg/m³), with a range of approximately 1.215(1215 Kg/m³) to approximately 1.300 (1300 Kg/m³).

The purpose of the separator is to physically separate and insulate theelectrodes from electrical conduction with one another, which wouldshort the battery, yet maintain ionic conduction between the electrodesvia the electrolyte, which is required for the electrochemical reactionof the battery. Therefore, the separator must be electricallynon-conductive (other than, for example, a carbon coating on one side)to electrically separate the electrodes, yet porous enough to allowionic conduction (such as via the electrolyte that fills the pores). Ifthe separator is too porous or has pores that are too large, thendendrites are likely to form large enough to bridge the gap between theelectrodes and short the battery. Extremely large pores may also allowdirect physical contact between the electrodes. Because the electrolytealso acts as a reactant, the separator must also allow enough acid tocontact and interact with the electrodes.

The reaction at the lead dioxide (PbO₂) positive (+) electrode (the“positive half-reaction”) supplies electrons and is left positive. Thispositive half-reaction during discharge at the lead dioxide (PbO₂)positive (+) electrode produces lead sulfate (PbSO₄) and water (H₂O),shown below in Eq. 1:

PbO₂+SO₄ ⁻²+4H⁺+2e ⁻↔PbSO₄+2H₂O  (Eq. 1)

where:

-   -   PbO₂ is the solid lead dioxide positive (+) electrode;    -   SO₄ ⁻² is aqueous;    -   4H⁺ is aqueous;    -   2e⁻ is in the solid lead dioxide (PbO₂) positive (+) electrode;    -   PbSO₄ is a solid precipitate within the aqueous electrolyte; and    -   H₂O is a liquid in the aqueous electrolyte.

The positive half-reaction is reversible upon charging the battery.

The negative half-reaction at the lead (Pb) negative (−) electrode (the“negative half-reaction”) supplies positive ions and is left negative.The negative half-reaction during discharge produces lead sulfate(PbSO₄) and negative ions (el, shown below in Eq. 2:

Pb+SO₄ ⁻²↔PbSO₄+2e ⁻  (Eq. 2)

where:

-   -   Pb is the solid lead negative (−) electrode;    -   SO₄ ⁻² is aqueous;    -   PbSO₄ is a solid precipitate within the aqueous electrolyte; and    -   2e⁻ is in the lead (Pb) negative (−) electrode;

The negative half-reaction is reversible upon charging the battery.

Together, these half-reactions give way to the overall chemical reactionof the lead acid battery, shown below in Eq. 3:

Pb+PbO₂+2H₂SO₄↔2PbSO₄+2H₂O  (Eq. 3)

where:

-   -   Pb is the solid negative (−) electrode;    -   PbO₂ is the solid positive (+) electrode;    -   H₂SO₄ is a liquid within the aqueous electrolyte;    -   PbSO₄ is a solid precipitate within the aqueous electrolyte; and    -   H₂O is a liquid within the aqueous electrolyte.

The overall chemical reaction is reversible upon charging the battery.For each of the above reactions, discharge occurs moving from left toright, and charging occurs moving right to left. During dischargingcycles, both the positive (+) and negative (−) electrodes convert atleast partially into lead sulfate (PbSO₄) and the electrolyte loses muchof its sulfuric acid (H₂SO₄) and becomes mostly water. As shown in FIG.2A, a predominately-discharged battery cell has two electrodes 52, 54 oflead sulfate and dilute sulfuric acid, with a separator 100 disposedbetween the electrodes 52, 54. As shown in FIG. 2B, a battery cell with100% charge has an electrode of lead dioxide 52, an electrode of lead54, a sulfuric acid electrolyte, with a separator 100 disposed betweenthe electrodes 52, 54.

A particular weakness of typical lead acid batteries operating in a PSoCis the production of lead sulfate (PbSO₄) during discharging cycles. Asshown in the equations above (see, Eq. 1, Eq. 2, and Eq. 3), bothelectrodes consume the sulfuric acid from the electrolyte, leaving theelectrolyte with a lower specific gravity. Simultaneously, theelectrodes at least partially convert to lead sulfate. The lead sulfateis more voluminous than lead, which leads to the active material (e.g.,NAM and PAM) swelling. If this active material is not restrained, itwill shed with time and shorten the life of the battery. When the activematerial is restrained, it maintains contact with the current carryinggrid and easily converts from lead sulfate to lead. Generally, theactive material is essentially unsupported in a typical flooded battery.In valve regulated lead acid (“VRLA”) batteries, the absorptive glassmat (“AGM”) separator provides more support in that it is in fullcontact with the active material. Though it provides support, the AGMseparator is infinitely compressible and does not fully resist theswelling of the active material during discharge. Though the AGMseparator may prevent shedding, the active material may lose electricalconnection to the current collector and remain in the sulfated state.

Another particular weakness of typical lead acid batteries operating ina PSoC is that the electrolyte becomes stratified. During chargingcycles, the electrodes convert from the sulfated state while producingsulfuric acid (H₂SO₄). The acid produced is at a higher concentrationthan that of the rest of the electrolyte, which is diluted sulfuricacid. In addition, sulfuric acid is more dense than water. Therefore,the bulk of the produced acid will sink to the bottom of thecell/battery and ultimately stratify with a higher concentration of acidat the bottom of the electrolyte. Acid stratification shortens life ofthe battery, deteriorates battery electrical performance, and can causebattery management systems to yield false signals that the battery ischarged.

Yet another particular weakness of typical lead acid batteries operatingin a PSoC relates to the fact that the battery is typically located inthe vehicle's engine bay. For a variety of reasons, vehiclemanufacturers are continuously optimizing the use of the volume within avehicle. As such, the engine bay has become smaller and more and morecrowded resulting in reduced airflow through the engine bay. Withreduced airflow and operation in hot climates, a typical lead acidbattery may see temperatures in excess of 80° C. the positive electrodemay produce oxidizing species at the surface that can degrade typicalpolyethylene separators. Furthermore, elevated temperatures onlyaccelerate by orders of magnitudes the oxidizing reactions that furtherhasten the degradation of polyethylene separators.

There remains a need to, at least partially, address the above problemsor issues relating to weaknesses known to typical lead acid batteriesoperating in a PSoC. The present application and inventors provide, asdescribed herein, a novel battery separator that will preferably provideadequate support against active material swelling, reduce, mitigate, oreliminate acid stratification, and be highly oxidative resistant. Thesame novel separator will preferably maintain current benefits ofexisting separators, such as polyethylene separators, that include lowionic resistance, good puncture resistance, envelopability, and remainhighly cost effective. As of this application filing, the inventors knowof no battery separator that is capable of providing all thesecharacteristics in the fashion or embodiments described herein.Accordingly, the present invention preferably aims to meet at leastthese and other heretofore-largely unmet needs.

SUMMARY

For at least certain applications or batteries, the details of one ormore exemplary embodiments, aspects, or objects of the present inventionat least provide for battery separators having a variable overallthickness, such as an overall thickness that varies as a function ofpressure applied to the separator. Other features, objects, andadvantages of the present invention provide for reduced battery failure,improved battery cycle life, and/or improved performance. Moreparticularly, there remains a need to provide a separator capable ofadapting to varying electrode spacing, during at least one of thebattery's production and/or in use after its manufacture.

The details of one or more exemplary embodiments, aspects, or objectsare in the detailed description and claims set forth hereinafter. Otherfeatures, objects, and advantages will be apparent from the detaileddescription and claims set forth hereinafter. In accordance with one ormore select embodiments, aspects, or objects, the present disclosure orinvention at least addresses the problems, issues, or needs enumeratedherein, and in some cases provides a solution that surprisingly andunexpectedly exceeds needs and expectations.

In accordance with at least certain exemplary embodiments, objects, oraspects, the present disclosure or invention may provide novel orimproved separators, cells, batteries, systems, methods of manufacture,use, and/or applications of such novel or improved separators, cells,batteries, and/or systems that overcome at least the aforementionedproblems. For example, at least certain exemplary embodiments, objects,or aspects provide batteries with separators that are adaptable toelectrodes with varied spacing therebetween, and by providing batterieswith separators having variable thicknesses.

In accordance with at least selected exemplary embodiments, aspects, orobjects, the present disclosure or invention provides a separator whosecomponents and physical attributes and features synergistically combineto address, in surprising and unexpected ways, previously unmet needs inthe lead acid battery industry with an improved battery separator. Incertain preferred exemplary embodiments, the present disclosure orinvention provides a battery using a separator as described herein toaddress, in surprising and unexpected ways, previously unmet needs inthe lead acid battery industry with an improved lead acid batteryseparator. In certain preferred exemplary embodiments, the presentdisclosure or invention provides a system using a battery as describedherein to address, in surprising and unexpected ways, previously unmetneeds in the lead acid battery industry with an improved systemutilizing an inventive lead acid battery that utilizes an inventiveseparator as described herein.

In accordance with at least certain embodiments, the present disclosureor invention relates to novel or improved separators, cells, batteries,systems, and/or methods of manufacture and/or use and/or applications ofsuch novel separators, cells, batteries, and/or systems. In accordancewith at least certain embodiments, the present disclosure or inventionis directed to novel or improved battery separators for: lead acidbatteries; flooded lead acid batteries; enhanced flooded lead acidbatteries (“EFBs”); flat-plate batteries; tubular batteries; deep-cyclebatteries; batteries operating in a partial state of charge (“PSoC”);valve regulated lead acid (“VRLA”) batteries; gel batteries; absorptiveglass mat (“AGM”) batteries; inverter batteries; stationary batteries;batteries used while in motion; energy storage for electricitygeneration, such as by steam turbine generators, such as by coal and/orgas fired power plants, and/or nuclear power plants; energy storage forelectricity generation by solar power, wind power, hydro-electric power,or other alternate and/or renewable energy sources; general energystorage batteries; uninterruptible power source (“UPS”) batteries;batteries with high cold-cranking ampere (“CCA”) requirements; vehiclebatteries, such as starting-lighting-ignition (“SLI”) vehicle batteries,idling-start-stop (“ISS”) vehicle batteries, marine batteries,automobile batteries, truck batteries, motorcycle batteries, all-terrainvehicle batteries, forklift batteries, golf cart (also referred to asgolf cars) batteries, hybrid-electric vehicle (“HEV”) batteries,electric vehicle batteries, light electric vehicle batteries,neighborhood electric vehicle (“NEV”) batteries, e-rickshaw batteries,e-trike batteries, e-bike batteries, electric scooter batteries; and/orthe like; and/or combinations thereof. In accordance with selectembodiments, the present disclosure or invention relates to batteryseparators for use in systems or vehicles incorporating theabove-mentioned batteries. In accordance with at least certain aspects,the present disclosure or invention relates to improved methods ofmaking and/or using such improved separators, cells, batteries, systems,and/or the like.

In one aspect, a battery separator is described that comprises, consistsof, or consists essentially of the following: (1) a polymeric substrate;and (2) a material layer provided on at least one surface of thepolymeric substrate. In some preferred embodiments, the material layermay be provided on two or two or more surfaces of the polymericsubstrate.

Regarding the polymeric substrate, in preferred embodiments, thepolymeric substrate is a flexible polymeric substrate. In someembodiments, the oil content of the polymeric substrate is from 1 to20%, from 1 to 10%, or from 1 to 5%. The polymeric substrate may be anonwoven or a woven polymeric substrate. The polymeric substrate may bea sheet or an envelope.

In some preferred embodiments, the polymeric substrate is a polymericporous membrane having a positive face and a negative face, where eachof the positive face and the negative face optionally have ribs,protrusions, or both ribs and protrusions. The porous polymeric membranemay have pores with an average pore size is less than about 1 micron.The polymeric porous membrane may be perforated, microporous,nanoporous, macroporous, or mesoporous. The polymeric porous membranemay comprise a polyolefin, including at least one of polyethylene,polypropylene, and blends or copolymers thereof. The polymeric porousmembrane may also further comprise a filler in addition to thepolyolefin.

In embodiments where ribs are present, the ribs may be at least oneselected from continuous ribs, discontinuous ribs, longitudinallyextending ribs, latitudinally extending ribs, diagonally extending ribs,integral ribs, non-integral ribs, and mini ribs. In some embodimentswhere ribs are present on a face of the porous membrane, ribs,protrusions, or both ribs and protrusions may not be present on one ormore outer edges of the membrane. In such embodiments, if ribs orprotrusions are present on one or more outer edges of the membrane, thenthey will be mini ribs or mini protrusions. Mini ribs or protrusions mayhave a height of, at most, 100 microns to 250 microns from a face of thepolymeric porous membrane.

The thickness of the polymeric substrate may range from 50 to 500microns. In embodiments where ribs, protrusions, or both ribs andprotrusions are formed on a face of the substrate, the thickness of thebackweb (not including the rib height) is 50 to 500 microns. In someembodiments, the combined thickness of the polymeric substrate and thematerial layer may be from 125 microns to 4 mm.

Regarding the material layer, the material layer may be provided on thepositive face, on the negative face, or on both the positive and thenegative face of the polymeric porous membrane described above. Thematerial layer may be provided on a side or face having ribs,protrusions, or both ribs and protrusions, or the material layer may beprovided on a side or face that does not have ribs, does not haveprotrusions, or does not have ribs or protrusions. In embodiments wherethe material layer is provided on a side or face that does have ribs,protrusions, or both ribs and protrusions, the material layer may beprovided at least between any two ribs, any two protrusions, or betweena rib and a protrusions. However, in embodiments where mini ribs or miniprotrusions are present on an outer edge of the membrane, it ispreferred that the material layer is not provided between these miniribs, between these mini protrusions, or between a mini rib and a miniprotrusion.

In embodiments where the material layer is provided between two ribs,between two protrusions, or between a rib and a protrusion, the materiallayer may partially fill, completely fill, or overfill the area betweentwo ribs, between two protrusions, or between a rib and a protrusion.

In some preferred embodiments, the material layer comprises, consistsof, or consists essentially of a material that has an oil absorptiongreater than 15 g of oil/100 g. The oil absorption of the material mayalso be greater than 25 g of oil/100 g of the material, from 25 g ofoil/100 g of the material to 100 g of oil/100 g of the material, from 25g of oil/100 g of the material to 200 g of oil/100 g, of from 25 g ofoil/100 g of the material to 300 g of oil/100 g of the material.

The material may be at least one selected from the group consisting ofsilica, precipitated silica, fumed silica, a talc, diatomaceous earth, apolysulfone, a polyester, PVC, and combinations thereof. In someembodiments, the material may be an organic or inorganic particulatethat is at least one of hydrophilic, acid loving, and acid stable. Insome embodiments, the material may comprise particles with differentaverage sizes.

In some embodiments, the material layer may comprise, consist of, orconsist essentially of the material as described above and a binder. Thebinder may be present in an amount less than 50%, and in someembodiments may be present in an amount between 1-20%. The binder may beone that is soluble, partially soluble, or insoluble in a battery acidsuch as H2SO4.

In some embodiments, the material layer may further comprise, consistof, or consist essentially of at least one additional material. Theadditional material does not necessarily have to have the oil absorptioncharacteristics of the material, but it can. The additional material, insome preferred embodiments, is at least one selected from the groupconsisting of carbon, a water-loss-reducing agent, a fatty alcohol, asurfactant, a wetting agent, a zinc salt, any other batteryperformance-enhancing additive, and combinations thereof.

In some embodiments, the material or the material layer may have a bulkdensity in the range of 0.1 to 3.5 g/cm³.

In some embodiments, an additional layer is provided on the materiallayer. The additional layer may comprise, consist of, or consistessentially of at least one selected from the group consisting ofcarbon, a water-loss-reducing agent, a fatty alcohol, a surfactant, awetting agent, a zinc salt, a metal sulfate, any other batteryperformance-enhancing additive, and combinations thereof. The additionallayer may also comprise, consist of, or consist essentially of a binderor other additive, or combinations thereof.

In another aspect, a lead acid battery, which may include a flooded leadacid battery or a valve-regulated lead acid battery, is describedherein. In some embodiments, the lead acid battery may comprise thefollowing: (1) a negative plate; (2) a positive plate; (3) anacid-containing electrolyte; and (4) a battery separator as describedherein that is placed between at least one negative and at least onepositive plate. The lead acid battery may be a cylindrical-cell-type ora prismatic-cell-type.

The material layer of the battery separator may be formed between thepolymeric substrate and the positive plate, between the polymericsubstrate and the negative plate, or between the polymeric substrate andboth the positive and the negative plate.

In some embodiments, an additional layer may be formed between thepolymeric substrate and the negative and/or positive plates. Theadditional layer may comprise, consist of, or consists essentially of atleast one of carbon, a water-loss-reducing agent, a fatty alcohol, asurfactant, a wetting agent, a zinc salt, a metal sulfate, any otherbattery-performance-enhancing additive, and combinations thereof.

The lead acid battery described hereinabove or the battery separatorcontained therein may exhibit or does at least one, at least two, atleast three, or all of the following properties: (1) immobilizes atleast a portion of the acid-containing electrolyte; (2) is notinfinitely compressible; (3) improves oxidation resistance allowing forthinner and more porous base or substrate material; or (4) restrainsactive material in at least one of the positive or negative plates (NAMor PAM).

In another aspect, a Valve-Regulated Lead Acid (VRLA) battery isdescribed herein. The improvement of the VRLA described herein is thereplacement of at least one absorptive glass mat (AGM) with a batteryseparator as described herein. The VRLA battery may be acylindrical-cell-type or a prismatic-cell-type.

The material layer of the battery separator may be formed between thepolymeric substrate and a positive plate of the VRLA battery, betweenthe polymeric substrate and a negative plate of the VRLA, or between thepolymeric substrate and both a positive and a negative plate of the VRLAbattery.

In some embodiments, an additional layer may be formed between thepolymeric substrate and the negative and/or positive plates. Theadditional layer may comprise, consist of, or consists essentially of atleast one of carbon, a water-loss-reducing agent, a fatty alcohol, asurfactant, a wetting agent, a zinc salt, any otherbattery-performance-enhancing additive, and combinations thereof.

The VRLA battery or the separator therein may exhibit, one, two, or allof the following properties: (1) immobilizes at least a portion of theacid-containing electrolyte; (2) is not infinitely compressible; and (3)restrains active material in at least one of the positive or negativeplates (NAM or PAM).

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a schematic cutaway side-view of a typical lead acid batteryhaving a plurality of alternating positive (+) electrodes and negative(−) electrodes, and separators interleaved therebetween.

FIG. 2A is a schematic of a typical lead acid battery cell in asubstantially discharged state. FIG. 2B is a schematic of a lead acidbattery cell in a substantially charged state.

FIG. 3A is a plan-view depiction of a typical separator having a firstsurface or face with a plurality of ribs longitudinally disposedthereon, extending therefrom, and being substantially parallel to themachine direction. FIG. 3B shows a plan-view depiction of the separatorshown in FIG. 3A having a second surface or face, opposite to the firstsurface or face, with a plurality of optional negative cross-ribs 106laterally disposed thereon, extending therefrom, and being substantiallyparallel to the cross-machine direction.

FIG. 4A is an end-view representation of a typical separator havingmajor ribs and a flat backweb. FIG. 4B is an end-view representation ofa typical separator having major ribs and negative cross-ribs 106 on anopposite surface.

FIG. 5A is an end-view illustration of a typical electrode/separatorassembly in a fully charged state. FIG. 5B is an end-view illustrationof a typical electrode/separator assembly in a fully discharged state.FIG. 5C is a section-view detail along line A-A of FIG. 5A.

FIG. 6A is an end-view schematic of an exemplary embodiment of thepresent invention having positive ribs. FIG. 6B is an end-view schematicof an exemplary embodiment of the present invention having a flat porousmembrane without ribs. FIG. 6C is an end-view drawing of anelectrode/separator assembly with the separator of FIG. 6A in either acharged or a discharged state. The material layer is designated 210 inthese Figures.

FIG. 7A is a section-view along line B-B of FIG. 6C. FIG. 7B is a sideview detail similar to that of FIG. 7B, with an exemplary inventiveseparator with negative cross-ribs.

FIG. 8A is a plan-view of an exemplary embodiment with flat backwebseparator without ribs, protrusions, or ribs and protrusions. If ribs orprotrusions are present in the side regions, they are mini ribs orprotrusions. FIGS. 8B and 8C are end views of exemplary embodiments asenvelope separators. Back web is 202 and side regions without ribs orprotrusions are 212. 200 denotes the separator. 214 denotes a sealedarea of the formed envelopes shown in 8B and 8C.

FIG. 9 is an end-view schematic of an exemplary embodiment of thepresent invention having positive ribs.

DETAILED DESCRIPTION

Described herein is an improved battery separator for a lead acidbattery, including a flooded lead acid battery or valve regulated leadacid (VRLA) battery. The battery separator described herein may alsoreplace one or more absorptive glass mats (AGMs) in a VRLA battery.There are many benefits of using the improved battery separatordescribed herein. One benefit is that the battery separator describedherein is not infinitely compressible like a typical AGM. Anotherbenefit of the battery separator described herein is its ability torestrain liquid electrolyte, which may help in preventing acidstratification, which as explained hereinabove negatively effectsbattery life and performance. Another benefit that the battery separatordescribed herein may exhibit is an ability to restrain negative activematerial (NAM), positive active material (PAM) or both NAM and PAM,which may swell, grow, and/or expand during battery operation. Thesebenefits, in addition to others, are realized by the improved batteryseparator disclosed herein.

Battery Separator

The structure of the battery separator described herein is not solimited, but in preferred embodiments, the battery separator may havethe following structure: (1) a substrate and (2) a material layer formedon at least one surface or face of the substrate. In other embodiments,another layer (3) may be formed as part of the structure. Theparticulars of the substrate, the material layer, and the optional otherlayer are described above and in more detail below.

(1) Substrate

The substrate of the battery separator is not so limited and may bepolymeric or non-polymeric. It may be porous or non-porous. However, inpreferred embodiments, the substrate is flexible, polymeric, and porousor perforated. For example, many commercially available batteryseparators sold by DARAMIC® may be used as the polymeric substrate ofthe battery separator described herein. For example, Daramie HiCharge™,Daramic® HP™, DuraLife®, Daramic® HD™, or Daramic® HD Plus™, Darak®,XCHarge™, HiCharge™, Daramic® EFS™, or Daramic® IND CL™ may be used. Thesubstrate may be formed by a variety of processes including, but notlimited to an extrusion process, a casting process, a process typicalfor forming a nonwoven including a spun bond process, or a processtypical for forming a woven.

The composition of the polymeric substrate is not so limited. Thepolymeric substrate may have a composition that includes at least one ofthe polymers, thermoplastic polymers, polyvinyl chlorides (“PVCs”),phenolic resins, natural or synthetic rubbers, synthetic wood pulp,lignins, glass fibers, synthetic fibers, cellulosic fibers, and/orcombinations thereof. The natural or synthetic rubbers may include oneor more of rubber, latex, natural rubber, synthetic rubber, cross-linkedor uncross-linked natural or synthetic rubbers, cured or uncuredrubbers, crumb or ground rubber, polyisoprenes, methyl rubber,polybutadiene, chloroprene rubbers, butyl rubber, bromobutyl rubber,polyurethane rubber, epichlorhydrin rubber, polysulphide rubber,chlorosulphonyl polyethylene, polynorbornene rubber, acrylate rubber,fluorine rubber and silicone rubber and copolymer rubbers, such asstyrene/butadiene rubbers, acrylonitrile/butadiene rubbers,ethylene/propylene rubbers (“EPM” and “EPDM”) and ethylene/vinyl acetaterubbers, and/or combinations thereof.

In some aspects of the present invention, the polymeric substrate'scomposition may further possess a filler. In some embodiments, thatfiller is at least one of silica, dry finely divided silica,precipitated silica, amorphous silica, highly friable silica, alumina,talc, fish meal, fish bone meal, barium sulfate (BaSO₄), carbon,conductive carbon, graphite, artificial graphite, activated carbon,carbon paper, acetylene black, carbon black, high surface area carbonblack, graphene, high surface area graphene, ketjen black, carbonfibers, carbon filaments, carbon nanotubes, open-cell carbon foam, acarbon mat, carbon felt, carbon Buckminsterfullerene (“Bucky Balls”), anaqueous carbon suspension, flake graphite, oxidized carbon, and/orcombinations thereof.

In some embodiments, the composition of the polymeric substrate mayfurther comprise a processing oil left over from manufacture of thesubstrate. One benefit of the battery separator described herein is theability to reduce processing oil content in the substrate below 20%,below 15%, below 10%, or below 5%. For example, the processing oilcontent may be reduced as low as 1% or less, 2% or less, 3% or less, 4%or less, 5% or less, 6% or less, 7% or less, 8% or less, 9% or less, 10%or less, 11% or less, 12% or less, 13% or less, 14% or less, 15% orless, 16% or less, 17% or less, 18% or less, 19% or less, or 20% orless. Conventionally, significant amounts of processing oil was leftbehind was to, among other things, improve oxidation resistance.However, with the addition of the material layer on at least one surfaceof the polymeric substrate in the battery separator described herein,the concern of oxidation resistance of the substrate is lower andamounts of remaining processing oil in the substrate can be reduced.Reducing the amount of processing oil can have the positive effect ofincreasing ionic conductivity of the substrate and/or lowering theelectrical resistance across the substrate. Thus, the ability to havelower amounts of remaining processing oil in the substrate issignificant and may lead to improved separator performance. Although theability to lower processing oil content of the substrate is a benefitmade possible by the structure of the improved battery separatordescribed herein, embodiments of the battery separator where thesubstrate has a processing oil content above 20% are also workable andhave other benefits.

In some embodiments, one or more surface or face of the substrate mayhave ribs, protrusions, or both ribs and protrusions. In embodimentswhere ribs are present, the ribs do not have any particular structurebut the may be at least one of the following: continuous ribs,discontinuous ribs, longitudinally extending ribs, latitudinallyextending ribs, diagonally extending ribs, integral ribs, non-integralribs, mini ribs, and combinations thereof. For example, the ribs couldbe discontinuous and diagonally extending ribs. Protrusions are notribs. One example of a protrusions may include, but is not limited to,dimples. When ribs, protrusions, or ribs and protrusions are formed onboth faces of the substrate, the types of ribs, protrusions, or ribs andprotrusions formed on each face or surface may be the same or different.For example, latitudinally extending ribs may be formed on one face orsurface of the substrate and longitudinally extending ribs may be formedon the other face or surface.

In some embodiments when ribs, protrusions, or ribs and protrusions areformed on a surface of the substrate, one or more edge regions of thesubstrate may not include ribs, protrusions, or ribs and protrusions orthe one or more edge regions may only include mini ribs, miniprotrusions, or mini ribs and protrusions. A mini rib or mini protrusionmay have a maximum height from the face of the substrate to the highestpoint of the rib or protrusion that is at most 100 to at most 250microns from the face of the substrate. In some embodiments, the maximumheight may be at most 75 microns, at most 50 microns, at most 25microns, at most 125 microns, at most 150 microns, at most 175 microns,at most 200 microns, or at most 225 microns. This type of structure maybe useful if the final structure of the battery separator is a pouch orsleeve that involves welding of the edges of the substrate material toform. In such embodiments where regions with no ribs or protrusions (oronly mini ribs or protrusions) are formed, it is preferred that nomaterial layer be formed in these regions either.

In some embodiments, the thickness of the substrate may be in the rangeof 50 to 500 microns, 75 to 500 microns, 100 to 500 microns, 125 to 500microns, 150 to 500 microns, 175 to 500 microns, 200 to 500 microns, 225to 500 microns, 250 to 500 microns, 300 to 500 microns, 325 to 500microns, 350 to 500 microns, 375 to 500 microns, 400 to 500 microns, 425to 500 microns, 450 to 500 microns, or 475 to 500 microns. Inembodiments, where ribs are formed on one or more surfaces of thesubstrate, the thickness of the substrate is the thickness of what isoften referred to the backweb, which is the substrate not consideringthe height of the ribs formed thereon.

(2) Material Layer

The material layer is formed on one or more partial or entire surfacesof the substrate described herein above.

The composition of the material layer is not so limited. In someembodiments, the layer may comprise, consist of, or consist essentiallyof a material having an oil absorption value greater than 15 g ofoil/100 g of the material, greater than 25 g of oil/100 g of thematerial, greater than 50 g of oil/100 g of the material, greater than75 g of oil/100 g of the material, greater than 100 g of oil/100 g ofthe material, greater than 125 g of oil/100 g of the material, greaterthan 150 g of oil/100 g of the material, greater than 175 g of oil/100 gof the material, greater than 200 g of oil/100 g of the material,greater than 225 g of oil/100 g of the material, greater than 250 g ofoil/100 g of the material, greater than 275 g of oil/100 g of thematerial. The oil absorption value may be 20, 30, 40, 50, 60, 70, 80,90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220,230, 240, 250, 260, 270, 280, 290, or 300 g of oil/100 g of thematerial. In some embodiments, the oil absorption value of the materialis from 25 g of oil/100 g of material to 300 g of oil/100 g of thematerial. Oil absorption is used as the measure here as a proxy for theamount of battery acid that might be absorbed into the material. Oilabsorption may be measured by the appropriate ASTM test method for aparticular material or any other suitable method for measuring oilabsorption. Porosity, overall surface areas, and other features of amaterial are properties that may affect the oil absorption value of agiven material.

In some embodiments, the material may have a bulk density in the rangefrom 0.1 to 3.5 g/cm³, in the range from 0.2 to 3.5 g/cm³, in the rangefrom 0.3 to 3.5 g/cm³, in the range from 0.4 to 3.5 g/cm³ in the rangefrom 0.5 to 3.5 g/cm³ in the range from 0.6 to 3.5 g/cm³, in the rangefrom 0.7 to 3.5 g/cm³, in the range from 0.8 to 3.5 g/cm³, in the rangefrom 0.9 to 3.5 g/cm³ in the range from 1.0 to 3.5 g/cm³ in the rangefrom 1.1 to 3.5 g/cm³, in the range from 1.2 to 3.5 g/cm³, in the rangefrom 1.3 to 3.5 g/cm³, in the range from 1.4 to 3.5 g/cm³ in the rangefrom 1.5 to 3.5 g/cm³ in the range from 1.6 to 3.5 g/cm³, in the rangefrom 1.7 to 3.5 g/cm³, in the range from 1.8 to 3.5 g/cm³, in the rangefrom 1.9 to 3.5 g/cm³ in the range from 2.0 to 3.5 g/cm³ in the rangefrom 2.1 to 3.5 g/cm³, in the range from 2.2 to 3.5 g/cm³, in the rangefrom 2.3 to 3.5 g/cm³, in the range from 2.4 to 3.5 g/cm³ in the rangefrom 2.5 to 3.5 g/cm³ in the range from 2.6 to 3.5 g/cm³, in the rangefrom 2.7 to 3.5 g/cm³, in the range from 2.8 to 3.5 g/cm³, in the rangefrom 2.9 to 3.5 g/cm³ in the range from 3.0 to 3.5 g/cm³ in the rangefrom 3.1 to 3.5 g/cm³, in the range from 3.2 to 3.5 g/cm³, in the rangefrom 3.3 to 3.5 g/cm³, or in the range from 3.4 to 3.5 g/cm³. In someembodiments, the bulk density may be less than 0.1 g/cm³ or greater than3.5 g/cm³.

In some embodiments, the material of the material layer may comprise,consist of, or consist essentially of at least one selected from silica,precipitated silica, fumed silica, a talc, diatomaceous earth, apolysulfone, a polyester, PVC, and combinations thereof.

In some embodiments, the material may comprise, consist of, or consistessentially of one or more organic or inorganic particulates having atleast one of the following properties: being hydrophilic, being acidloving, and being acid stable.

In some embodiments, the material may further comprise, consist of, orconsist essentially of a battery-performance-enhancing additive. Theadditive is not so limited, but may be, for example, at least oneselected from a wetting agent, a surfactant, a water-loss-reducingagent, an agent for increasing charge acceptance, a fatty alcohol, azinc salt, carbon, and combinations thereof.

In some embodiments, the material has a single average particle sizewith a wide or narrow particle size distribution. In some embodiments,the material includes a first portion with a first average particle sizeand particle size distribution and a second portion with a seconddistinct (smaller or larger) average particle size and a particle sizedistribution that is overlapping or non-overlapping with the particledistribution of the first portion. Without wishing to be bound by anyparticular theory, it is believed that having at least two portions withdifferent particle sizes and/or different particle size distributionsmay help increase the packing density of the material.

In some embodiments, the material layer may further comprise, consistof, or consist essentially of a binder. For example, in some embodimentsthe material layer may comprise, consist of, or consist essentially ofthe material as described above and a binder or the material, a binder,and an additive such as a battery-performance-enhancing additive. Insome embodiments, the amount of binder in the material layer may be 50%or less, 45% or less, 40% or less, 35% or less, 30% or less, 25% orless, 20% or less, 15% or less, 10% or less, 5% or less, 4% or less, 3%or less, 2% or less, or 1% or less.

The type of binder used is not so limited. In some preferredembodiments, the binder may be a polymeric binder. In some embodiments,the binder may be insoluble, partially soluble, or soluble in batteryacid such as H₂SO₄. In some embodiments, it may be preferred for thebinder to be soluble or partially soluble in battery acid such that whenthe battery separator described herein is placed in a lead acid battery,part of the binder will dissolve possibly leaving the material layermore porous than it was before the battery separator was placed into thebattery.

In some embodiments, the material layer itself may have a bulk densityin the range from 0.1 to 3.5 g/cm³, in the range from 0.2 to 3.5 g/cm³,in the range from 0.3 to 3.5 g/cm³, in the range from 0.4 to 3.5 g/cm³,in the range from 0.5 to 3.5 g/cm³, in the range from 0.6 to 3.5 g/cm³,in the range from 0.7 to 3.5 g/cm³, in the range from 0.8 to 3.5 g/cm³,in the range from 0.9 to 3.5 g/cm³, in the range from 1.0 to 3.5 g/cm³,in the range from 1.1 to 3.5 g/cm³, in the range from 1.2 to 3.5 g/cm³,in the range from 1.3 to 3.5 g/cm³, in the range from 1.4 to 3.5 g/cm³,in the range from 1.5 to 3.5 g/cm³, in the range from 1.6 to 3.5 g/cm³,in the range from 1.7 to 3.5 g/cm³, in the range from 1.8 to 3.5 g/cm³,in the range from 1.9 to 3.5 g/cm³, in the range from 2.0 to 3.5 g/cm³,in the range from 2.1 to 3.5 g/cm³, in the range from 2.2 to 3.5 g/cm³,in the range from 2.3 to 3.5 g/cm³, in the range from 2.4 to 3.5 g/cm³,in the range from 2.5 to 3.5 g/cm³, in the range from 2.6 to 3.5 g/cm³,in the range from 2.7 to 3.5 g/cm³, in the range from 2.8 to 3.5 g/cm³,in the range from 2.9 to 3.5 g/cm³, in the range from 3.0 to 3.5 g/cm³,in the range from 3.1 to 3.5 g/cm³, in the range from 3.2 to 3.5 g/cm³,in the range from 3.3 to 3.5 g/cm³, or in the range from 3.4 to 3.5g/cm³. In some embodiments, the bulk density may be less than 0.1 g/cm³or greater than 3.5 g/cm³. The bulk density may be measured before orafter the material layer (as part of the battery separator) has beenused in a lead acid battery as described herein.

In some embodiments, the material layer may be applied to a surface ofthe substrate described herein that has ribs, protrusions, or ribs andprotrusions. In some embodiments, the material layer is applied to asurface or face of the substrate that does not have any ribs or anyprotrusions. In some embodiments, the material layer is provided on asurface that has ribs or protrusions and on a surface or face that doesnot have any ribs or protrusions.

When the material layers is provided on a face or surface with ribs,protrusions, or both ribs and protrusions, the material layers isprovided in an area between at least two ribs, at least two protrusions,or a rib and a protrusion. In some embodiments, there may be a materiallayer present in the area between all the ribs, all the protrusions, orall the ribs and protrusions. In some embodiments, there may be amaterial layer present only in the area between some ribs, someprotrusions, or some ribs and protrusions. The material layer maypartially fill, completely fill, or over fill the area between two ribs,two protrusions, or a rib and a protrusion. Partially filled may meanthat between 1 and 99% of the area is filled. In some preferredembodiments, it may mean that 50% or more, 60% or more, 70% or more, 80%or more, 90% or more, or 95% or more of the area is filled.

(3) Another Optional Layer

In some embodiments, an optional layer may be provided in contact withthe material layer. The composition of the optional layer is not solimited. In some embodiments, the layer may comprise, consist of, orconsist essentially of one or more battery-performance-enhancingadditive as described herein. In some embodiments, the layer maycomprise, consist of, or consist essentially of one or morebattery-performance-enhancing additive as described herein and one ormore binders as described herein. In some embodiments, the layer maycomprise, consist of, or consist essentially of one or morebattery-performance-enhancing additive as described herein, one or morebinders as described herein, and another additive.

The optional layer may have a thickness from 1 to 300 microns, 1 to 250microns, 1 to 200 microns, 1 to 150 microns, 1 to 100 microns, or 1-50microns.

In some embodiments, one or more battery-performance-enhancing additivesmay be present in the material layer and in the another optional layer.

Battery

Any battery separator described herein may be used in a lead acidbattery, particularly a flooded-type lead acid batter or valve regulatedlead acid (VRLA) battery. In a valve-regulated lead acid battery, thebattery separator described herein may replace at least one absorptiveglass mat (AGM), some of the AGMs, or all of the AGMs. The batteryseparator described herein offers several benefits compared to an AGMbattery separator. As one example, the battery separator is notinfinitely compressible like an AGM, which offers advantages in at leasta cylindrical-type battery cell. Being infinitely compressible is alsoan undesirable from a standpoint of withstanding pressure due topositive active material (PAM) and negative active material (NAM)swelling during battery operation.

The structure of the lead acid battery is not so limited, but inpreferred embodiments, the lead acid battery may comprise at least thefollowing: (1) a positive electrode or plate, (2) a negative electrodeor plate, (3) a battery separator as described herein between thepositive and negative plate, and (4) an electrolyte. The active layer ofthe battery separator described herein may be on a side closest to thepositive plate, on a side closest to the negative plate, or on a sideclosest to the negative plate and a side closest to the positive plate.

In accordance with at least certain aspects, objects or embodiments, thepresent application or invention may address or at least partiallyaddress, some of the above mentioned problems or issues relating toknown to typical lead acid batteries operating in a PSoC. In accordancewith at least certain aspects, objects or embodiments, the presentapplication or invention provides, as described herein, a novel batteryseparator that will preferably provide adequate support against activematerial swelling, reduce, mitigate, or eliminate acid stratification,and be highly oxidative resistant. The same novel separator willpreferably maintain current benefits of existing separators, such aspolyethylene separators, that include low ionic resistance, goodpuncture resistance, envelopability, and remain highly cost effective.In accordance with at least certain aspects, objects or embodiments, thepresent invention preferably aims to meet at least these and otherheretofore-largely unmet needs.

Disclosed in at least one embodiment herein is a battery separatorcomprising a substrate that may be polymeric and porous. The substratemay have ribs, protrusions, or ribs and protrusions on one or both facesor surfaces thereof. On at least one surface or face of the substrate, amaterial layer may be formed. The material layer may contain a materialwith an oil absorption value equal to or greater than 15 g oil/100 g ofmaterial. The battery separator disclosed herein is useful in a leadacid battery, particularly in a flooded lead acid battery or avalve-regulated lead acid (VRLA) battery. The battery separatordescribed herein has many benefits including helping mitigate or preventissues such as acid stratification and others that may deterioratebattery performance or battery life.

In some embodiments, the lead acid battery may be acylindrical-cell-type or a prismatic-cell type lead acid battery, anaccumulator, a storage battery, or the like.

The separator may be calendered to for example, set the final height orthickness, to compact the coating or material, and/or the like.

In the batteries described herein, the battery separator performs one,two, three, or all four of the following: immobilizes at least a portionof the acid-containing electrolyte helping with acid stratification; isnot infinitely compressible, which helps with cell manufacture; andrestrains active material in at least one of the positive or negativeplates (NAM or PAM) because unrestrained NAM or PAM may shed; improvesoxidation resistance allowing for the use of thinner and more porousbase material in the separator as described in the Examples below.

When used herein, solubility in acid may be determined in some instancesby looking at a material's (e.g., a binder's) oxidation resistance inthat acid. Low oxidation resistance may indicate a soluble binder andhigh oxidation resistance may indicate an insoluble binder. A partiallysoluble binder would have a mid-range (between high and low) oxidationresistance.

When used herein, hydrophilicity of a material may be determined in someinstances by looking at the wet out time of the separator having amaterial layer comprising, consisting of, or consisting essentially ofthat material. For example, a wet out time less than 10 minutes, lessthan 9 minutes, less than 8 minutes, less than 7 minutes, less than 6minutes, less than 5 minutes, less than 4 minutes, less than 3 minutes,less than 2 minutes, less than 1 minute, or less than 30 seconds. Lessthan 3 minutes is preferable in some instances.

When used herein, the acid loving nature of a material may be determinedin some instances by looking at the wet out time of the separator havinga material layer comprising, consisting of, or consisting essentially ofthat material. For example, a wet out time less than 10 minutes, lessthan 9 minutes, less than 8 minutes, less than 7 minutes, less than 6minutes, less than 5 minutes, less than 4 minutes, less than 3 minutes,less than 2 minutes, less than 1 minute, or less than 30 seconds. Lessthan 3 minutes is preferable in some instances.

When used herein, the term acid stable may be determined in someinstances by looking at a material's oxidation resistance in acid. Amaterial with low oxidation resistance is considered less stable in acidthan a material with high oxidation resistance. A weight loss test maybe performed to measure oxidation resistance.

EXAMPLES Example 1—PE Ribbed Substrate+Silica Material Layer on RibbedSide Used in Flooded Lead Acid Battery

As a starting point, the novel invention will be first explained inturns of the separator used in an Enhanced Flooded Battery (EFB). TheEFB has a typical electrode spacing of approximately 0.8 mm. In thisspace, a PE separator (substrate) is placed. The backweb of theseparator is typically 0.20 mm and the ribs that protrude from thissurface are another 0.60 mm, thus the total thickness of the separatoris 0.80 mm. A typical automotive separator may have 11 to 30 ribs acrossthe surface of the separator. The present invention, in some embodimentstakes the typical PE separator and applies highly porous silicaparticles having an oil absorption greater than 15 g of oil/100 g ofsilica in the space between the ribs. To function in highly automatedequipment the silica will have to be attached to the separator substrateand to adjacent silica particles. The action of binding or adhering thesilica can be done by appropriate selection of chemicals currentlyavailable. For example a binder as described herein is used.

To start, the silica agglomerate is approximately 85% porous in and ofitself. Then, as the particles are randomly arranged in the spacebetween the ribs, they will create a semi-rigid porous structure toserve a multitude of purposes. First, the semi-rigid porous structurewill uniformly support the active material that swells during discharge.In this way the active material will not be unsupported and allowed toswell and form large crystals of stable lead sulfate and effectivelynon-porous and prevent the acid from reacting with the active material.These large areas are predominately consist of lead sulfate, whicheffectively an insulator and a highly effective barrier for the acid tohave intimate contact with the active lead particles. Left in this statelong enough, the large areas of lead sulfate will ultimately losecontact and from the other active material and shed off the electrodesurface area. The benefit of the invention is the silica-coatedseparator will uniformly support the active material, prevent regions ofswelling and create optimum utilization of active material and extendlife when it is due to active material shedding. In applications wherelaminates such as glass mats or pasting papers are used to minimizeactive material shedding, they can be suppressed and the presentinvention can be employed.

After shedding, the layer of highly porous silica with high surface areawill be useful to immobilize the acid preventing stratification. Uponcharging, pure sulfuric acid is generated at the electrode surface. Thisacid has density higher than the bulk acid and will tend to stratify.With a layer of silica pressed up against the positive electrode, theacid will be held in place by the interstitial porous structure of thesilica. The primary manner to overcome acid stratification is toovercharge the battery and produce oxygen and hydrogen with theelectrolysis of water. These gases will rise in the acid and evacuatethrough the vent ports. As they rise, the gases will carrying the heavyliquids upward and mix the acid. However, in a partial state of chargeoperation, the battery may not necessarily see an overcharge conditionand therefore the primary means of acid mixing is gone. In addition, ifwe can prevent acid stratification, then we no longer need an overchargecondition. Minimizing the number of overcharge conditions will lowerwater loss and slow down the rate of grid corrosion.

Another benefit of the current invention can be seen in regard to theoxidation attack. As electrodes are made thinner, the associatedseparator spacing is also made thinner. Therefore, the opportunity foroxidative attack on the separator increases. With regard to this attack,it is critical the back web thickness or the continuous substrate of theseparator is not compromised. If it is compromised with a hole, crack orsplit, this is a place for electronic conductance to occur from opposingelectrodes, which would result in a short. As the oxidizing attack isinitiated at the positive electrode, the silica-coated surface willprovide an extra layer of oxidation protection. With this layer ofsilica on the substrate, one could even think of making the substratethinner (<150 microns) or greater porosity (>62%) or the combination ofboth. Separator with thinner backweb and higher porosity will result inlower separator ionic or electrical resistance thus providing greaterpower for the battery during a high discharge.

All the benefits described can also be applied lead acid batteries usedin other applications such as golf cart, renewable energy, back-up powerand a means of energy for electric fork trucks. In these applications,the electrode spacing is typically thicker and thus the overallthickness of the separator is also greater than those found in anautomotive battery. Yet the benefits application of this new separatorcan also be applied in a similar manner.

Example 2—PE Ribbed Substrate+Silica Material Layer on Ribbed Side Usedin a Valve-Regulated Lead Acid (VRLA) Battery

Example 1 is describing the flooded lead acid batteries. However, onecould imagine that the aforementioned silica coated separator (PE ribbedsubstrate+silica material layer on the ribbed side) could also work innon-flooded applications also called starve electrolyte of valveregulated lead acid (VRLA) batteries. These come in few configurations.First, configuration is what is commonly called a gel or Dry-fitbattery. In this application, a polyethylene or cross-linked separator,the acid electrolyte is mixed with fumed silica to create a thixotropiccondition and then added to the battery. In this condition, theelectrolyte is immobilized, which prevents stratification. With thisparticular invention, no thixotropic condition is needed; the acid canbe added to the battery and silica coated separator will serve toimmobilize the electrolyte.

Another type of VRLA battery is often referred to as an AGM battery.Here, the separator is comprised of absorptive micro fiber glass matalso known as an AGM separator. These separators sufficiently immobilizethe acid; however, they have some deficiencies. In general, the pores ofthe AGM separator range from five to 25 microns and thus they do notsufficiently provide protection against shorting. Thus, when AGMbatteries are used in deep cycling application, they are likely to faildue to shorts. Therefore, the idea is to use a sub-micron substrate,such as the PE separator, and coat it with highly porous silica. The PEseparator or substrate will provide short protection while the layer ofsilica will be used to immobilize the acid. This present invention maybe very useful in AGM batteries that have very thin plate spacing (e.g.<1.0 mm) such as e-bike, e-car, thin foil or even bi-polar batteries.The battery separator described herein could replace any one of the AGMsin an AGM VRLA battery.

Example 3

There is another embodiment of this invention that is worth considering.Currently, the immediate application is to coat silica on an existingseparator and thus far, the examples have described a PE separator.However, silica could be coated onto other types of separators such asthose comprised of rubber, cross-linked phenolic resin and syntheticwood pulp. If the layer of silica provide a sufficiently small porestructure that prevent formation of pores (<5 microns), then a submicronsubstrate is no longer required. Therefore, another embodiment is tocoat a thin non-woven web with a layer of silica. In this manner, thenon-woven layer serves as a carrier web that allows a silica layer to betransferred to the battery. This non-woven could be a polymeric or evenmade from cellulosic materials such as currently used to produce pastingpapers.

Example 4

In this Example, the PE substrate of Example 1 is coated with a mixtureof silica and carbon on a negative face of the substrate or the facethat will face the negative electrode or plate in the battery.

Example 5

In this Example, the PE substrate of Example 1 has silica coated acrossan entire face of the substrate. In this manner, the separator can beused to wrap the electrodes or plates.

Example 6

In this Example, the PE substrate of Example 1 is coated with silicaover a majority of the surface, except leaving an outer strip uncoated.The outer strip is preferably unribbed or has only mini ribs. In thisway, the separator can be enveloped and sealed unto itself.

Example 7

In this embodiment, the PE substrate is microporous, but has no ribs orprotrusions. A silica material layer is applied on at least one surfacethereof. It may be a partial surface or an entire surface coating. In anembodiment 7a, silica is applied on both faces or surfaces of the PEsubstrate. It may be applied on an entire or partial surface.

Example 8

This Example is like Example 1, except the silica layer has a waterlossadditive mixed in with the silica.

Example 9

This Example is like Example 1 except that the PE substrate is replacedwith a non-woven or woven material.

Example 10

This Example is like Example 1 except that carbon may be applied to anegative face or surface of the substrate.

1. A battery separator comprising: a polymeric substrate or flexiblespine that is porous, microporous, or nonporous; and a material layer,wherein the material layer comprises, consists of, or consistsessentially of a material that has an oil absorption greater than 15 gof oil/100 g of material to 300 g of oil/100 g of material and whereinthe material layer is provided on at least one surface of the polymericsubstrate.
 2. The battery separator of claim 1, the material has an oilabsorption from 25 g of oil/100 g of material to 100 g of oil/100 g ofmaterial.
 3. (canceled)
 4. The battery separator of claim 1, wherein thepolymeric substrate is a polymeric porous membrane having a positiveface and a negative face, and each of the positive face and the negativeface optionally have ribs (selected from continuous ribs, discontinuousribs, longitudinally extending ribs, latitudinally extending ribs,diagonally extending ribs, integral ribs, non-integral ribs, and miniribs), protrusions, or both ribs and protrusions; and the material layeris formed on at least one of the positive face, the negative face, orboth the positive face and the negative face.
 5. (canceled) 6.(canceled)
 7. (canceled)
 8. (canceled)
 9. (canceled)
 10. (canceled) 11.(canceled)
 12. The battery separator of claim 4, wherein at least oneouter edge of the polymeric porous membrane does not have ribs orprotrusions or has only mini ribs or mini protrusions, wherein mini ribsor protrusions have a height of at most 100 microns to 250 microns froma face of the polymeric porous membrane.
 13. The battery separator ofclaim 4, wherein the material layer is provided between at least tworibs on the polymeric porous membrane, at least 2 protrusions on thepolymeric porous membrane, or between a rib and a protrusion on thepolymeric porous membrane, but is not provided between any two mini ribsor mini protrusions on the polymeric porous membrane.
 14. The batteryseparator of claim 13, wherein the material layer completely fills,partially fills, or overfills an area between at least two ribs on thepolymeric porous membrane, at least 2 protrusions on the polymericporous membrane, or between a rib and a protrusion on the polymericporous membrane.
 15. (canceled)
 16. (canceled)
 17. (canceled) 18.(canceled)
 19. (canceled)
 20. The battery separator of claim 1 whereinthe polymeric porous membrane comprises a polyolefin and a filler. 21.(canceled)
 22. (canceled)
 23. The battery separator of claim 4, whereinthe polymeric porous membrane has ribs, protrusions, or both ribs andprotrusions on at least one face thereof, and the material layer isprovide on at least one of the following: a face of the polymeric porousmembrane that has ribs, protrusions, or both ribs and protrusions; or aface of the polymeric porous membrane that does not have ribs,protrusions, or both ribs and protrusions.
 24. (canceled)
 25. (canceled)26. The battery separator of claim 23, wherein the material layer isprovided on both of the following: a face of the polymeric porousmembrane that has ribs, protrusions, or both ribs and protrusions; and aface of the polymeric porous membrane that does not have ribs,protrusions, or both ribs and protrusions.
 27. The battery separator ofclaim 1, wherein the material layer or the material of the materiallayer has a bulk density of from 0.1 to 3.5 g/cm³.
 28. The batteryseparator of claim 1, wherein the material layer further comprises,consists of, or consists essentially of a binder, and: the binder ispresent in an amount less than 50%; the binder is present in an amountfrom 1 to 20%; the binder is soluble, partially soluble, or insoluble inbattery acid such as H₂SO₄.
 29. (canceled)
 30. (canceled)
 31. (canceled)32. (canceled)
 33. (canceled)
 34. (canceled)
 35. The battery separatorof claim 1, wherein the material layer further comprises, consists of,or consists essentially of at least one other material, wherein: thematerial is at least one selected from the group consisting of silica,precipitated silica, fumed silica, a talc, diatomaceous earth, apolysulfone, a polyester, PVC, and combinations thereof; the material isan organic or inorganic particulate that is at least one of hydrophilic,acid loving, and acid stable; the material comprises particles ofdifferent sizes; or the material is selected from the group consistingof carbon, a water-loss-reducing agent, a fatty alcohol, a surfactant, awetting agent, a zinc salt, any other battery performance-enhancingadditive, and combinations thereof.
 36. (canceled)
 37. (canceled) 38.(canceled)
 39. (canceled)
 40. The battery separator of claim 1, whereinanother material layer is provided on top of the material layer.
 41. Thebattery separator of claim 4, wherein at least one of the positive andthe negative face does not have any ribs or protrusions.
 42. (canceled)43. The battery separator of claim 1, wherein an oil content of thepolymeric substrate is from 1 to 20%, from 1% to 10%, or from 1% to 5%.44. (canceled)
 45. (canceled)
 46. The battery separator of claim 1,wherein the polymeric substrate is a woven or nonwoven polymericsubstrate, a sheet, or an envelope.
 47. (canceled)
 48. A lead acidbattery, including a flooded lead acid battery or a valve-regulated leadacid battery, comprising: a negative plate; a positive plate; anacid-containing electrolyte; and a battery separator between thepositive and the negative plate, wherein the battery separator is abattery separator as described in claim
 1. 49. The lead acid battery ofclaim 48, wherein the lead acid battery is a cylindrical-cell-type leadacid battery or a prismatic-cell-type lead acid battery.
 50. (canceled)51. The lead acid battery of claim 48, wherein the material layer isformed: between the polymeric substrate and the positive plate; Betweenthe polymeric substrate and the negative plate; or between both thepolymeric substrate and the positive plate and between the polymericsubstrate and the negative plate.
 52. (canceled)
 53. (canceled)
 54. Thelead acid battery of claim 48, wherein the lead acid battery is avalve-regulated lead acid battery or a flooded lead acid battery. 55.(canceled)
 56. The lead acid battery of claim 48 wherein at least oneadditional layer is formed between the polymeric substrate and thepositive plate, between the polymeric substrate and the negative plate,or between both the polymer substrate and the positive plate and betweenthe polymeric substrate and the negative plate, and wherein theadditional layer comprises at least one of carbon, a water-loss-reducingagent, a fatty alcohol, a surfactant, a wetting agent, a zinc salt, anyother battery-performance-enhancing additive, and combinations thereof.57. (canceled)
 58. The lead acid battery of claim 48, wherein thebattery separator does or exhibits at least one, at least two, at leastthree, or all four of the following: immobilizes at least a portion ofthe acid-containing electrolyte; improves oxidation resistance; is notinfinitely compressible; and restrains active material in at least oneof the positive or negative plates (NAM or PAM).
 59. (canceled) 60.(canceled)
 61. A Valve-Regulated Lead Acid (VRLA) battery, wherein theimprovement comprises replacing at least one absorptive glass mat (AGM)with a battery separator as described in claim
 1. 62. The VRLA batteryof claim 61, wherein the battery is a cylindrical-cell-type battery or aprismatic-cell-type battery.
 63. (canceled)
 64. The VRLA battery ofclaim 61, wherein at least one additional layer is formed between thepolymeric substrate and a positive plate, between the polymericsubstrate and a negative plate, or between both the polymer substrateand a positive plate and between the polymeric substrate and a negativeplate, and wherein the additional layer comprise at least one of carbon,a water-loss-reducing agent, a fatty alcohol, a surfactant, a wettingagent, a zinc salt, any other battery-performance-enhancing additive,and combinations thereof.
 65. (canceled)
 66. The VRLA battery of claim61, wherein the battery separator exhibits or does at least one, atleast two, at least three, or all four of the following: immobilizes atleast a portion of the acid-containing electrolyte; improves oxidationresistance; is not infinitely compressible; and restrains activematerial in at least one of the positive or negative plates (NAM orPAM).
 67. (canceled)
 68. (canceled)
 69. The battery separator of claim1, wherein the polymeric substrate has a thickness of 50 to 500 micronsor from 50 to less than 150 microns.
 70. The battery separator of claim69, wherein the combined thickness of the polymeric substrate and thematerial layer is from 100 microns to 4 mm.
 71. (canceled)
 72. Thebattery separator of claim 1, wherein the polymeric substrate has aporosity greater than 50%, greater than 55%, greater than 60%, greaterthan 65%, greater than 70%, greater than 75%, greater than 80%, greaterthan 85%, or greater than 90%.
 73. (canceled)